ISOLATION AND CHARACTERIZATION OF DESULFITOBACTERIUM DEHALOGENANS GEN-NOV, SP-NOV, AN ANAEROBIC BACTERIUM WHICH REDUCTIVELY DECHLORINATES CHLOROPHENOLIC COMPOUNDS

An organism that is able to reductively ortho-dechlorinate 2,4-dichlor ophenol and 3-chloro-4-hydroxyphenylacetate (3-Cl-4-OHPA) was isolated from a methanogenic lake sediment. This organism, an anaerobic, motil e, Gram-type-positive, rod-shaped bacterium, grew in the presence of 0 .1% yeast extract when pyruvate, lactate, formate, or hydrogen was use d as the electron donor for reductive dehalogenation of 3-Cl-4-OHPA. S ulfite, thiosulfate, and sulfur were reduced to sulfide, nitrate was r educed to nitrite, and fumarate was reduced to succinate. Dissimilator y reduction of sulfate could not be demonstrated, and no adenylylsulfa te reductase was detected with an immunoassay. The organism fermented two pyruvate molecules to one lactate molecule, one acetate molecule, and one carbon dioxide molecule. The pH and temperature optima for bot h growth and dechlorination of 3-Cl-4-OHPA were 7.5 and 38 degrees C, respectively. The doubling time under these conditions was approximate ly 3.5 h. On the basis of the results of a 16S rRNA analysis and the i nability of the organism to use sulfate as an electron acceptor, strai n JW/IU-DC1 is described as the type strain of the new taxon Desulfito bacterium dehalogenans gen. nov., sp. nov.